1. Field of the Invention
The present invention relates to a smell sensing element and a smell sensing device using the element.
2. Description of the Prior Art
It is known to evaluate smell or odor by human olfactories, by a gas chromatograph or by a gas sensor constituted by use of such a metal oxide semiconductor as SnO.sub.2 (Japanese patent laid-open under No. 54-114296).
However, the first method using the human olfactories has the disadvantages of troublesome evaluation procedures and of difficult and expertise-requiring evaluation. The second method using gas chromatograph has the disadvantages of its great size and its unsuitability for portable use and its incapability of speedy real-time analysis. On the other hand, by the third method using a metal oxide semiconductor as the sensing element, the device may be miniaturized for portable use. However, the device needs some improvements in its sensitivity and precision and the same has been incapable of providing precise evaluation.